Java tutorial
package org.bouncycastle.bcpg; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.util.Vector; import org.bouncycastle.bcpg.sig.IssuerKeyID; import org.bouncycastle.bcpg.sig.SignatureCreationTime; import org.bouncycastle.util.Arrays; /** * generic signature packet */ public class SignaturePacket extends ContainedPacket implements PublicKeyAlgorithmTags { private int version; private int signatureType; private long creationTime; private long keyID; private int keyAlgorithm; private int hashAlgorithm; private MPInteger[] signature; private byte[] fingerPrint; private SignatureSubpacket[] hashedData; private SignatureSubpacket[] unhashedData; private byte[] signatureEncoding; SignaturePacket(BCPGInputStream in) throws IOException { version = in.read(); if (version == 3 || version == 2) { int l = in.read(); signatureType = in.read(); creationTime = (((long) in.read() << 24) | (in.read() << 16) | (in.read() << 8) | in.read()) * 1000; keyID |= (long) in.read() << 56; keyID |= (long) in.read() << 48; keyID |= (long) in.read() << 40; keyID |= (long) in.read() << 32; keyID |= (long) in.read() << 24; keyID |= (long) in.read() << 16; keyID |= (long) in.read() << 8; keyID |= in.read(); keyAlgorithm = in.read(); hashAlgorithm = in.read(); } else if (version == 4) { signatureType = in.read(); keyAlgorithm = in.read(); hashAlgorithm = in.read(); int hashedLength = (in.read() << 8) | in.read(); byte[] hashed = new byte[hashedLength]; in.readFully(hashed); // // read the signature sub packet data. // SignatureSubpacket sub; SignatureSubpacketInputStream sIn = new SignatureSubpacketInputStream(new ByteArrayInputStream(hashed)); Vector v = new Vector(); while ((sub = sIn.readPacket()) != null) { v.addElement(sub); } hashedData = new SignatureSubpacket[v.size()]; for (int i = 0; i != hashedData.length; i++) { SignatureSubpacket p = (SignatureSubpacket) v.elementAt(i); if (p instanceof IssuerKeyID) { keyID = ((IssuerKeyID) p).getKeyID(); } else if (p instanceof SignatureCreationTime) { creationTime = ((SignatureCreationTime) p).getTime().getTime(); } hashedData[i] = p; } int unhashedLength = (in.read() << 8) | in.read(); byte[] unhashed = new byte[unhashedLength]; in.readFully(unhashed); sIn = new SignatureSubpacketInputStream(new ByteArrayInputStream(unhashed)); v.removeAllElements(); while ((sub = sIn.readPacket()) != null) { v.addElement(sub); } unhashedData = new SignatureSubpacket[v.size()]; for (int i = 0; i != unhashedData.length; i++) { SignatureSubpacket p = (SignatureSubpacket) v.elementAt(i); if (p instanceof IssuerKeyID) { keyID = ((IssuerKeyID) p).getKeyID(); } unhashedData[i] = p; } } else { throw new RuntimeException("unsupported version: " + version); } fingerPrint = new byte[2]; in.readFully(fingerPrint); switch (keyAlgorithm) { case RSA_GENERAL: case RSA_SIGN: MPInteger v = new MPInteger(in); signature = new MPInteger[1]; signature[0] = v; break; case DSA: MPInteger r = new MPInteger(in); MPInteger s = new MPInteger(in); signature = new MPInteger[2]; signature[0] = r; signature[1] = s; break; case ELGAMAL_ENCRYPT: // yep, this really does happen sometimes. case ELGAMAL_GENERAL: MPInteger p = new MPInteger(in); MPInteger g = new MPInteger(in); MPInteger y = new MPInteger(in); signature = new MPInteger[3]; signature[0] = p; signature[1] = g; signature[2] = y; break; case ECDSA: MPInteger ecR = new MPInteger(in); MPInteger ecS = new MPInteger(in); signature = new MPInteger[2]; signature[0] = ecR; signature[1] = ecS; break; case EDDSA: MPInteger edR = new MPInteger(in); MPInteger edS = new MPInteger(in); signature = new MPInteger[2]; signature[0] = edR; signature[1] = edS; break; default: if (keyAlgorithm >= PublicKeyAlgorithmTags.EXPERIMENTAL_1 && keyAlgorithm <= PublicKeyAlgorithmTags.EXPERIMENTAL_11) { signature = null; ByteArrayOutputStream bOut = new ByteArrayOutputStream(); int ch; while ((ch = in.read()) >= 0) { bOut.write(ch); } signatureEncoding = bOut.toByteArray(); } else { throw new IOException("unknown signature key algorithm: " + keyAlgorithm); } } } /** * Generate a version 4 signature packet. * * @param signatureType * @param keyAlgorithm * @param hashAlgorithm * @param hashedData * @param unhashedData * @param fingerPrint * @param signature */ public SignaturePacket(int signatureType, long keyID, int keyAlgorithm, int hashAlgorithm, SignatureSubpacket[] hashedData, SignatureSubpacket[] unhashedData, byte[] fingerPrint, MPInteger[] signature) { this(4, signatureType, keyID, keyAlgorithm, hashAlgorithm, hashedData, unhashedData, fingerPrint, signature); } /** * Generate a version 2/3 signature packet. * * @param signatureType * @param keyAlgorithm * @param hashAlgorithm * @param fingerPrint * @param signature */ public SignaturePacket(int version, int signatureType, long keyID, int keyAlgorithm, int hashAlgorithm, long creationTime, byte[] fingerPrint, MPInteger[] signature) { this(version, signatureType, keyID, keyAlgorithm, hashAlgorithm, null, null, fingerPrint, signature); this.creationTime = creationTime; } public SignaturePacket(int version, int signatureType, long keyID, int keyAlgorithm, int hashAlgorithm, SignatureSubpacket[] hashedData, SignatureSubpacket[] unhashedData, byte[] fingerPrint, MPInteger[] signature) { this.version = version; this.signatureType = signatureType; this.keyID = keyID; this.keyAlgorithm = keyAlgorithm; this.hashAlgorithm = hashAlgorithm; this.hashedData = hashedData; this.unhashedData = unhashedData; this.fingerPrint = fingerPrint; this.signature = signature; if (hashedData != null) { setCreationTime(); } } /** * get the version number */ public int getVersion() { return version; } /** * return the signature type. */ public int getSignatureType() { return signatureType; } /** * return the keyID * @return the keyID that created the signature. */ public long getKeyID() { return keyID; } /** * return the signature trailer that must be included with the data * to reconstruct the signature * * @return byte[] */ public byte[] getSignatureTrailer() { byte[] trailer = null; if (version == 3 || version == 2) { trailer = new byte[5]; long time = creationTime / 1000; trailer[0] = (byte) signatureType; trailer[1] = (byte) (time >> 24); trailer[2] = (byte) (time >> 16); trailer[3] = (byte) (time >> 8); trailer[4] = (byte) (time); } else { ByteArrayOutputStream sOut = new ByteArrayOutputStream(); try { sOut.write((byte) this.getVersion()); sOut.write((byte) this.getSignatureType()); sOut.write((byte) this.getKeyAlgorithm()); sOut.write((byte) this.getHashAlgorithm()); ByteArrayOutputStream hOut = new ByteArrayOutputStream(); SignatureSubpacket[] hashed = this.getHashedSubPackets(); for (int i = 0; i != hashed.length; i++) { hashed[i].encode(hOut); } byte[] data = hOut.toByteArray(); sOut.write((byte) (data.length >> 8)); sOut.write((byte) data.length); sOut.write(data); byte[] hData = sOut.toByteArray(); sOut.write((byte) this.getVersion()); sOut.write((byte) 0xff); sOut.write((byte) (hData.length >> 24)); sOut.write((byte) (hData.length >> 16)); sOut.write((byte) (hData.length >> 8)); sOut.write((byte) (hData.length)); } catch (IOException e) { throw new RuntimeException("exception generating trailer: " + e); } trailer = sOut.toByteArray(); } return trailer; } /** * return the encryption algorithm tag */ public int getKeyAlgorithm() { return keyAlgorithm; } /** * return the hashAlgorithm tag */ public int getHashAlgorithm() { return hashAlgorithm; } /** * return the signature as a set of integers - note this is normalised to be the * ASN.1 encoding of what appears in the signature packet. */ public MPInteger[] getSignature() { return signature; } /** * Return the byte encoding of the signature section. * @return uninterpreted signature bytes. */ public byte[] getSignatureBytes() { if (signatureEncoding == null) { ByteArrayOutputStream bOut = new ByteArrayOutputStream(); BCPGOutputStream bcOut = new BCPGOutputStream(bOut); for (int i = 0; i != signature.length; i++) { try { bcOut.writeObject(signature[i]); } catch (IOException e) { throw new RuntimeException("internal error: " + e); } } return bOut.toByteArray(); } else { return Arrays.clone(signatureEncoding); } } public SignatureSubpacket[] getHashedSubPackets() { return hashedData; } public SignatureSubpacket[] getUnhashedSubPackets() { return unhashedData; } /** * Return the creation time of the signature in milli-seconds. * * @return the creation time in millis */ public long getCreationTime() { return creationTime; } public void encode(BCPGOutputStream out) throws IOException { ByteArrayOutputStream bOut = new ByteArrayOutputStream(); BCPGOutputStream pOut = new BCPGOutputStream(bOut); pOut.write(version); if (version == 3 || version == 2) { pOut.write(5); // the length of the next block long time = creationTime / 1000; pOut.write(signatureType); pOut.write((byte) (time >> 24)); pOut.write((byte) (time >> 16)); pOut.write((byte) (time >> 8)); pOut.write((byte) time); pOut.write((byte) (keyID >> 56)); pOut.write((byte) (keyID >> 48)); pOut.write((byte) (keyID >> 40)); pOut.write((byte) (keyID >> 32)); pOut.write((byte) (keyID >> 24)); pOut.write((byte) (keyID >> 16)); pOut.write((byte) (keyID >> 8)); pOut.write((byte) (keyID)); pOut.write(keyAlgorithm); pOut.write(hashAlgorithm); } else if (version == 4) { pOut.write(signatureType); pOut.write(keyAlgorithm); pOut.write(hashAlgorithm); ByteArrayOutputStream sOut = new ByteArrayOutputStream(); for (int i = 0; i != hashedData.length; i++) { hashedData[i].encode(sOut); } byte[] data = sOut.toByteArray(); pOut.write(data.length >> 8); pOut.write(data.length); pOut.write(data); sOut.reset(); for (int i = 0; i != unhashedData.length; i++) { unhashedData[i].encode(sOut); } data = sOut.toByteArray(); pOut.write(data.length >> 8); pOut.write(data.length); pOut.write(data); } else { throw new IOException("unknown version: " + version); } pOut.write(fingerPrint); if (signature != null) { for (int i = 0; i != signature.length; i++) { pOut.writeObject(signature[i]); } } else { pOut.write(signatureEncoding); } pOut.close(); out.writePacket(SIGNATURE, bOut.toByteArray(), true); } private void setCreationTime() { for (int i = 0; i != hashedData.length; i++) { if (hashedData[i] instanceof SignatureCreationTime) { creationTime = ((SignatureCreationTime) hashedData[i]).getTime().getTime(); break; } } } public static SignaturePacket fromByteArray(byte[] data) throws IOException { BCPGInputStream in = new BCPGInputStream(new ByteArrayInputStream(data)); return new SignaturePacket(in); } }